A magnetic tunnel junction (MTJ) generally comprises a “pinned” ferromagnetic layer(hereinafter the “fixed layer”) whose magnetization is oriented in the plane of the layer but is fixed so as to not be able to rotate in the presence of an applied magnetic field in a range of interest, and a “free” ferromagnetic layer (hereinafter the “free layer”) whose magnetization is able to be rotated in the plane of the layer relative to the fixed magnetization of the pinned ferromagnetic layer. Sandwiched between the fixed and the free layers the MTJ comprises an insulating tunnel barrier layer located between and in contact with both ferromagnetic layers. MTJs have been proposed for use in memory cells in a magnetic random access (MRAM) array.